Heretofore, conductive organic polymers such as polyaniline, polypyrrole, polyacetylene, and polythiophene have been used as battery electrode materials since they are light weight and flexible and have an oxidation-reduction function. Secondary batteries having such polymers incorporated as their electrode active material are known to provide improved charge/discharge efficiency and high energy density. Especially, the polyaniline is improved in cycle life and self discharge property over the other conductive organic polymers. There have been commercially available some batteries using polyaniline as positive electrode active material.
However, the batteries using polyaniline as positive electrode active material still have some problems to be cleared off for practical application.
In accordance with the recent trend for electric equipment to be of the cordless and digital types, an increasing number of equipment are required to generate and transmit digital signals. Small size batteries which are often used as a power supply for generating and transmitting digital signals have to perform well in a pulse discharge mode. However, the batteries using polyaniline or conductive organic polymers as their positive electrode active material cannot always provide satisfactory pulse discharge property for the reason that the conductive organic polymers are not so high in electric conductivity and for some reasons associated with the battery arrangement.
Further, these batteries can maintain sufficient discharge capacity during normal operation of the electric equipment which are loaded with the batteries. Often, such equipment are kept in stock for a long term before delivery to the consumer. Then the battery will spontaneously discharge during the warehouse storage. This leads to a possibility that after delivery to the consumer, the battery fail to discharge sufficient electricity upon actual use of the equipment.